Mark Cavendish prefers to deal in blunt certainty than evasive modesty and so the curly-haired young cyclist from the Isle of Man wastes no time on charming chit-chat. "I expect to do it," he says when asked about his dizzying ambition of following at least one stage win on the Tour de France with an Olympic gold medal alongside his British team-mate, Bradley Wiggins, in Beijing. "I'll be the best sprinter on the Tour and me and Brad will be the best Madison team in the Olympics. So why shouldn't we win? I know how hard I work and how hard Brad and my team work."

The intense 22-year-old initially appears curt as, with a shrug, he underlines his voracious appetite for success. If he is neither particularly eloquent nor overly warm, his conviction is as refreshing as it is compelling. "You could see at the end of the Giro d'Italia that I had a psychological edge over the other leading sprinters," Cavendish suggests of that illustrious race in May, where he won two stages and could have had another couple of victories rather than second-place finishes had he not made one small error and also allowed a team-mate a share of the glory. "They wouldn't try anything against me in the end so that's going to be a massive help on the Tour."

After pointing out that there are four sprint stages on the Tour next week, Cavendish answers coolly when asked which of these he might target. "All four. If it's a bunch sprint then I'm in with the best chance of anyone. I'll be disappointed if I don't win a stage. Obviously this is the Tour and you need some luck but when you know you're the fastest then something has to turn out right."

Cavendish made his Tour debut last year and is convinced that on the second day, from London to Canterbury, a first stage win was only denied by a cruel twist - after a zealous spectator stepped into his path. "It was 25km from the finish and I was up at the front. If I had been further back I would've been OK. The next thing I know I'm lying on the ground. I hit a woman. Apparently she had been told to stand back throughout the day. It's great that she wanted to watch but people are not aware how the sport works over here."

He grimaces when asked to describe his emotions after the crash. "You can see on TV that I'm gutted, I'm swearing. Imagine winning a stage on the Tour de France in Britain. For a British rider it's the biggest thing you can do and to have it ruined like that, not through any mistake I'd made, was really disappointing."

Cavendish's revelation that "I was crying my eyes out the last 15 miles" underlines his frustration after a race commissaire refused to allow him to benefit from cycling etiquette. "There's an unwritten rule that if you've crashed, or if you're behind through no fault of your own, then you get helped back to the peloton. But one commissaire stopped me doing that. It was his chance to work on the Tour and he thought his power was bigger than it was."

If he had been helped back to the peloton could he have still won the stage? Cavendish's nod is forceful: "Robbie McEwen got back," he says of the great Australian sprinter, "and he won."

Cavendish is not shy in bracketing himself with sprint legends. McEwen has won the Tour's green jersey, for overall points winner, three times and Erik Zabel, from Germany, won that title six years in a row. "Zabel's really good to me and we speak a lot. And with Robbie we have plenty in common and he's been a great help. The guy who got me my contract last year with T-Mobile also worked with Robbie at a young age and he said, from when I was 16, I was the next McEwen."

Against such a backdrop Cavendish insists he did not share the widespread surprise when he won 11 races in his debut season last year. McEwen only managed eight victories during his first year but Cavendish says: "I expected it. The hardest thing was getting the opportunity. When you're a young pro from an undeveloped country in road cycling then you're on the back foot. But I was given the opportunity and took it with both hands."

If Cavendish has won the hard-bitten approval of McEwen and Zabel his bullish assurance has upset many other rivals in a gladiatorial cycling discipline. When he produced his stunning victories at the Giro, Cavendish was accused of being "reckless" and "disrespectful" by the Italian sprinter Filippo Pozzato, who suggested Cavendish had held on to the back of his team car. "That's a lie," Cavendish snorts. "Has anyone ever seen me hold on to the back of a car? I don't do it. And now, because I work on my climbing and get over climbs, people think I've cheated. They can't understand I've gone home and worked hard. It's frustrating but, you know, he's a dickhead. I don't give a shit, really.

"Last year I was 21 and if you come in and win you're obviously going to get a name even if you're the nicest guy in the world. If you're winning bike races ahead of guys who're older than you then they're going to get upset. When some young guy appears from nowhere, some people who are slower assume they ride dangerously. But it's not the case. I'm the fastest - but it's not until you consistently do it that people start accepting you."

Cavendish earned more than acceptance at the Giro - in which only two other British cyclists, Vin Denson in 1966 and Robert Millar in 1987, have won a stage. He established himself as road cycling's quickest sprinter and as a resilient competitor who survived the toughest Italian tour in decades. It had been expected that he would drop out during the brutal mountain stages but Cavendish rode through "a few days of hell" to reach the finish in Milan.

"I was in an unbelievable state on the first mountain stage to Pampeago. I didn't eat enough and really suffered. Over a 180km stage, with the Alps, I felt really bad for six-and-a-half hours. I had blurry vision and I was shaking and wanted to sleep. My team wanted me to go home but I said no. So they let me have another day and I got better and better."

After such an experience Cavendish is irate when questions are raised about the prevalence of doping in cycling. "It's hurtful, but I know I'm doing everything right and I can be proud of my achievements."

Has he even been approached by a dope peddler? "No. If people think that they've got a very big misconception of cycling. Everyone thinks cycling is a big doping sport but Wimbledon is on at the minute. You can't tell me there're not dickheads [doing drugs] in that sport. If it's any sport, or any aspect of life, there're always people who think they're cleverer than the system. They anger me, these people, they really anger me. But you're going to get them and you've got to face it."

There seem to be a fair share of doping "dickheads" on every Tour? "Cycling is doing an active thing to combat the problem. Other sports aren't doing anything. They want to keep their image and franchise perfect. Cycling actually wants a clean and fair sport and so they're paying so much to get more anti-doping legislation to catch these cheats. In fact we're the cleanest sport around."

Cavendish, in his agitation, starts beating the table. The accusation of cheating in cycling clearly wears him down. "It does. But it's an unfortunate aspect of cycling that you're going to get these things said to you, or these suspicions thrown at you. But I want to be proud of what I've done and know that everything I've achieved has come through hard work."

Does he expect another doper to be exposed during this Tour? "I'd like to think there aren't any more people like that - you just don't know."

Cavendish repeats that doleful phrase four times before, finally, he returns to his preferred world of certainty - a stage win and Olympic gold with Wiggins in Beijing next month. He makes it all sound so easy, as if he merely needs to pop down to his local shop to pick up a pint of milk. "I've already shown how good I am. All the Tour will do is confirm that I'm a great sprinter rather than just a top-tier sprinter. I want to be remembered as a great sprinter. It's the same with the Olympics."

Which of his glittering goals will mean the most? "It depends what you want. If you want a lot of endorsements then you'd pick the Olympics. But I've had a passion for the Tour since I was a kid. Let's put it this way: it would be harder to win a stage on the Tour de France so that would mean more. I'd take the Tour win first - but I'm aiming for both."